If you try to turn the gearbox backwards, then ofc you get the gear ratio backwards. If that friction would make it able to turn by hand or not, dunno, but at 1:100 probably not. Try moving it the normal direction, forward way, at 100:1 and that way should turn.
I have had two cases of stuck gear boxes, in both cases some teeth parts splintered and got stuck in the other teeths and froze the whole assembly. I guess thats a common fail mode. If it is *really* stuck you might need to dismante and clean it. But probably that is not the case.
I have had two cases of stuck gear boxes, in both cases some teeth parts splintered and got stuck in the other teeths and froze the whole assembly. I guess thats a common fail mode. If it is *really* stuck you might need to dismante and clean it. But probably that is not the case.